Track-type machines typically include a track assembly having a plurality of interlocking links, each link being coupled to a ground-engaging traction panel. Adjacent links may be interconnected via a laterally disposed track pin to form a continuous chain. A bushing may be disposed about the track pin and configured to provide a rotatable interface at the surface of the track pin. The bushing is adapted to engage a portion of a sprocketed drive hub. As a drive motor rotates the sprocketed drive hub, teeth of the sprocketed drive hub engage spaces between the bushings forcing the track link to move in the direction of rotation of the hub, thereby propelling the machine.
In many conventional track-driven systems, as the track chain is rotated about the track frame, a surface of the idler wheel is configured to contact an upper edge (or “wear surface”) of each link, subjecting the upper edge of each link to a significant portion of the weight of the machine, particularly as the link is rotated between the idler wheel and the ground. This contact produces a high coefficient of friction between the surface of the idler wheel and the wear surface of the link. As a result, any slippage or shift between the idler wheel and the wear surface may cause a significant amount of wear at the idler wheel/link interface. If allowed to persist, such wear may potentially erode a groove on the surface of the link, causing a distinctive wear pattern commonly referred to as “scalloping.” Thus, in order to reduce repair and replacement costs resulting from idler/track link wear, a track assembly design that reduces wear at the idler/track link interface may be required.
At least one system for reducing idler/track link wear is described in U.S. Pat. No. 6,883,876 (the '876 patent) to Yamamoto et al. The '876 patent discloses a track assembly comprising a plurality of link members, whereby adjacent link members are connected together via laterally extending pin members having a bushing member mounted thereon for rotation of the bushing about the pin member. The track assembly also includes a roller frame having first and second end portions comprising first and second sprocketed idlers that are adapted to engage the bushings so as to reduce contact with a wear surface of the track linkage. The contact surface between each sprocket is substantially concave (or arcuate), so as to substantially conform to the shape and diameter of the link bushings.
Although the system of the '726 patent may reduce contact between the idler and the surface of the track link, significantly reducing idler and track link wear caused by grinding at the interface of the idler and track link, it may still produce a significant amount of noise and vibration. For example, the sprocketed idler assembly of the '726 patent is substantially concave in shape. Consequently, the sprocketed idler of the '726 patent is primarily designed to engage the bushings at the root of the gap between the sprocket teeth. As a result, while traveling over uneven terrain, where the weight of the vehicle shifts more dramatically than on even terrain, the bushing often contacts the root of the gap with enough force to produce significant vibration and noise. Thus, in order to further reduce noise and vibration associated with track-type machines, a system to dampen or reduce the force with which the idler contacts the bushings, may still be required.